Step-by-step explanation:
[tex]343 {x}^{3} - 64 \\ = {(7x)}^{3} - {(4)}^{3} \\ = ( 7x - 4) \{(7x)^{2} + 7x \times 4 + {(4)}^{2} \} \\ = ( 7x - 4) (49x^{2} + 28x + 16 )[/tex]
